Over approximately the past fifteen years arced sinuous spring band torsioning devices such as disclosed in U.S. Pat. No. 3,210,064, No. 3,388,904, and No. 3,525,514, have met the industry's long sought need for deep-drop and uplift at the back rail and contributed in other ways to the luxury seat which evolved. As eleven (11) and twelve (12) gauge helical spring connectors became disproportionally more expensive during this period, however, such torsioning devices came to be used almost exclusively with connector links such as disclosed in U.S. Pat. No. 3,790,149. As such, the cushion base means depend solely upon kinetic energy stored in the arced sinuous, for example, to produce desired back rail deep-drop and uplift in upholstered furniture.
The past few years in the furniture field have seen a move toward the use of thicker cushions. The use of thicker materials such as poly-foam laminates has necessitated lowering seat frame heights significantly. This has necessitated the use of cushion bases with a flat or virtually flat profiles. Deflection and uplift capability are severly limited by these configurations and, thus, less than desirable comfort, if not discomfort, is produced in the seat base assembly.
Regardless of what kind of cushion base is employed, however, the industry is interested in a product wherein both soft, deep-drop and upward resilience of a strong dynamic nature is achieved in the seat base assembly at minimal cost. The results achieved to date have been less than satisfactory.
The problem is particularly troublesome with wire-mesh cushion base means. Wire-mesh cushion base means have very little deflection capability and no self-contained upward resilience. The resulting seat base assembly produces an unyielding and relatively uncomfortable seat.
An area where the same problem has existed, unimproved for many years, is the automobile seat industry. There the weight, size, and space limitations of automobile seating have denied manufactures the capability of using effective seat enhancement devices and constructions. This is particularly true in the newer, smaller automobiles.
In general, the use of a flat wire mesh grid, or flat steel bands, gives a flat final profile. The minimal deflection provided under load is largely in the center of the span. This is anatomically unsuited for the human body in seated relationship. Much greater deflection is needed and should be located at the rear end of the span. Equally important, dynamic buoyancy, support and uplift are needed at the rear of the span.
Attempts to solve this seating deficiency have resulted in the use of horizontally installed helicals, heavy rubber inserts, and pivoting wire linkages and the like, at the back of the span. They have failed to give desired comfort. The sideward horizontal pull, or expansion and contraction, afforded by helicals or heavy rubber band type inserts is mechanically grossly inefficient and ineffective in permitting downward initial drop and subsequent deep-drop on one hand, or in generating progressive, dynamic upward buoyancy, resilience, or lift on the other hand.